[SOLVED] Shared library root path

[WitchCraft]

Hi!

Question: If I have a shared library e.g. libsomething.so
in /home/username/arbitraryFolder/libsomething.so

and load this shared library into a program, e.g.
/home/username/tools/sometool

how can I get the path of the shared library?
Meaning i want /home/username/arbitraryFolder/ back,
and not /home/username/tools/sometool

[WW]

Use the ldd command. For example, this shows the shared libraries used by the program aptitude:


$ ldd /usr/bin/aptitude
libapt-pkg-libc6.6-6.so.4.5 => /usr/lib/libapt-pkg-libc6.6-6.so.4.5 (0x00002ac9cbf4a000)
libncursesw.so.5 => /lib/libncursesw.so.5 (0x00002ac9cc217000)
libsigc-2.0.so.0 => /usr/lib/libsigc-2.0.so.0 (0x00002ac9cc47f000)
libpthread.so.0 => /lib/libpthread.so.0 (0x00002ac9cc684000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00002ac9cc8a0000)
libm.so.6 => /lib/libm.so.6 (0x00002ac9ccbab000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00002ac9cce2c000)
libc.so.6 => /lib/libc.so.6 (0x00002ac9cd03b000)
libutil.so.1 => /lib/libutil.so.1 (0x00002ac9cd396000)
libdl.so.2 => /lib/libdl.so.2 (0x00002ac9cd599000)
/lib64/ld-linux-x86-64.so.2 (0x00002ac9cbd2c000)
$

[arkangel]

the ldd command will show you the path only if the library is either on a location point by LD_LIBRARY_PATH , in a trusted directory (/lib, /usr/lib , etc ) or it is in a directory listed on /etc/ld.so.conf

I assume you library is not any of this places so ldd will giye you the name of the library but not its path,

if you can compile the application, one way to make it to remember where the library is (even if it is not in any of the places I mentioned before ) is to use the rpath switch

gcc -W1,rpath,/path/library/lib -L /path/library/lib my_file.c -lsomething

[stroyan]

A program can find the paths of the shared libraries it has loaded using dl_iterate_phdr().
There is a small complete example in "man dl_iterate_phdr".
That function is specific to linux and not portable to other posix systems.

[WitchCraft]

A program can find the paths of the shared libraries it has loaded using dl_iterate_phdr().
There is a small complete example in "man dl_iterate_phdr".
That function is specific to linux and not portable to other posix systems.

This is what i search, for Linux.
Is there a POSIX portable equivalent?

[WitchCraft]

Bump. Anybody knows how this is done on UNIX ?

[WitchCraft]

bump. Need it to work on UNIX, too...

[WitchCraft]

It's actually simple:

Read /proc/self/maps and parse it.
On FreeBSD, one has to remember it's called
/proc/curproc/maps

So to do it universially: /proc/<pid>/maps



string strMaps = System.IO.File.ReadAllText("/proc/self/maps");

string strPattern = @"([\w-]+)\s+([\w-]+)\s+([\w\d]+)\s+([\w\d:]+)\s+(\d+)\s+(.*)?";
System.Text.RegularExpressions.Regex myreg = new System.Text.RegularExpressions.Regex(strPattern);

// http://www.csharp411.com/c-read-string-line-by-line/
using (System.IO.StringReader reader = new System.IO.StringReader( strMaps ))
{
string strThisLine;
while ((strThisLine = reader.ReadLine()) != null)
{
Console.WriteLine("Line: " + strThisLine );

System.Text.RegularExpressions.Match mLineMatch = myreg.Match(strThisLine);
if(mLineMatch.Success)
{
foreach(System.Text.RegularExpressions.Group gThisGroup in mLineMatch.Groups)
{
Console.WriteLine("Group: " + gThisGroup.Value.ToString());
}
}
else
{
Console.WriteLine("Crap");
}
} // Whend
} // End Using